The present invention relates generally to magnetic disc recording systems and more particularly to a suspension device for supporting one or more magnetic transducers against a moving magnetic disc surface.
Reference is made to U.S. Pat. No. 4,245,267 entitled Suspension Device for Magnetic Transducers, in the name of Robert W. Herman, the applicant herein, and assigned to the same assignee as the present invention, the disclosure of which is hereby incorporated by reference.
Magnetic disc recording systems commonly utilize one or more magnetic transducers that are urged toward a rotating magnetic disc by suspension devices of various designs. The magnetic transducers ride against a fluid bearing formed between the magnetic heads and the rotating disc. Magnetic transducers of this type are often referred to as "flying" heads.
Various suspension devices are known which employ leaf springs to provide loading force which biases a magnetic transducer toward the surface of the magnetic disc. The leaf springs are generally affixed at one end to a suitable support and, at the other opposite end, contact or are secured to the magnetic transducer. Several suspension devices employing leaf springs are disclosed, for example, in U.S. Pat. Nos. 3,177,495, 3,512,253 and 3,573,768.
Such suspension devices, however, can in effect cause the loading force application point to vary as the loading force varies, causing undesirable rotational torques about the pitch axis of the transducer. For example, with the transducer rigidly affixed at or near the end of the leaf spring, the arc described by the leaf spring varies slightly as the loading applied to the transducer varies, thereby in effect shifting the loading force application point and thus causing the transducer pitch angle to vary. This loading may vary as a result of the magnetic transducer following surface imperfections in the rotating disc surface, often termed disc "runout", or as the load spring is adjusted to increase the loading force which biases the transducer toward the disc. This pitch variation can cause, among other difficulties, variations or loss of the signal being reproduced by the transducer or can cause the leading edge of the transducer to be rotated into the surface of the rotating disc, consequently causing a head crash with the ensuing loss of data and operating time.
As a further example, it is known to couple the magnetic transducer to the leaf spring by means of loosely fitting pins as is disclosed, for example, in U.S. Pat. No. 3,573,768. However, as the loading force applied by the leaf spring varies, the transducer tends to rock against the leaf spring contact surface, again varying the loading force application point and in turn causing the transducer pitch to undesirably vary.
In magnetic disc recording systems where the transducer is withdrawn from the surface of the disc when the disc is no longer rotated, it is further desirable to control the pitch attitude of the magnetic transducer as it nears the rotating disc surface during system start-up to thereby avoid damage to the transducer or the disc if an improper landing attitude is present. However, suspension devices employing leaf springs commonly provide no means for controlling this landing attitude and thus can cause the magnetic disc recording system to fail.